Radar Scattering Cross Section Research Articles

Modeling of the internal wave wake of a self-propelled body for radar scattering cross sections

The motion of a self-propelled body excites internal waves that modulate wind-induced microscale waves and affect the radar scattering cross section of rough sea surfaces. This process is closely related to factors such as stratification, propulsion effect, and radar parameters. Based on this, this study establishes and partially verifies a computational model for the scattering cross section of the internal wave wake left by an underwater self-propelled body. The model incorporates the first-order resonant internal waves of the stratified flow field as the dominant component of the wake-effect internal waves and determines the equivalent source size using the wake evolution model, thereby effectively simulating the characteristics of the surface flow field when the net momentum of the underwater vessel is nonzero. By solving the wave-action conservation equations, the wave spectrum of the modulated surface is derived, and the tilt and convergence/divergence effects caused by internal waves are comprehensively considered through the facet scattering model to assess their impact on the synthetic aperture radar (SAR) scattering cross section. Overall, this study systematically elucidates the correlation mechanism between the flow field and the radar system.

Electromagnetic scattering of cylindrical artificial electron cloud by using parabolic equation method

Abstract The ionizable metal vapor released in the ionosphere can artificially generate space electron clouds. They can scatter radio waves at decameter and meter wavelengths so as to realize over-the-horizon propagation. Based on the parabolic equation (PE) method and using Padé-(1,1) polynomial, the electromagnetic scattering characteristics of cylindrical artificial electron clouds are preliminarily studied in this letter. The bistatic radar scattering cross section (RCS) and the ground received field distribution via artificial electron cloud are calculated for various incidence angles at different radio frequencies and distances. The PE method is used here since its advantages of high precision, fast computing and less computing resource occupation over traditional methods. The study of electromagnetic scattering is valuable to the follow-up release experiments for generating electron cloud. It throws a new light on the practical utilization of over-the-horizon radio communication via scattering channel of artificial electron clouds.

A novel rGO-ZnFe2O4 hollow microsphere composite with excellent microwave absorption properties

In order to develop lightweight, efficient and broadband microwave absorbing materials, rGO-ZnFe2O4 hollow microsphere composites were prepared by the solution method in this paper. The effects of reduced graphene oxide (rGO) content on the microstructure of hollow microspheres and the microwave absorption properties of the material were studied. rGO micropowders and ZnFe2O4(ZFO) particles are uniformly distributed on the hollow microspheres. The rich porous hollow structure is conducive to the multiple reflection and scattering of electromagnetic microwaves. This structure and distribution state enable the composite material to have good impedance and form a synergistic effect of multiple absorption effects. The results show that the minimum reflection loss (RLmin) is −28.83 dB and the effective absorption bandwidth(EAB) is 5.92 GHz (11.04∼16.96 GHz) when the thickness is 2.00 mm and the rGO is 6.3 wt.%. The Radar scattering cross section(RCS) results show that the RCS values of the samples with the rGO is 6.3 wt.% are mostly below −20 dBm2 in the range of microwave incidence angle of −90°< Theta < 90°, which indicates the composites has wide-angle microwave absorption ability. This study provides a new approach to the design and preparation of efficient and lightweight electromagnetic microwave absorbing materials.

Exceeding natural resonance frequency limit and enhanced microwave absorption performance of Fe3O4 nanorods coated with SiO2 layer

Fe3O4@SiO2 composites with different morphologies (hollow nanorods, porous nanorods, and flower-like nanoparticles) were constructed using different preparation methods. Considerably enhancement of resonance frequency and permeability beyond Snoek’s limitation were observed in the Fe3O4@SiO2 composites with shape anisotropy and porous core-shell nanostructure. The resonance frequency of porous Fe3O4@SiO2 nanorods enhanced to 4.21 GHz, which is much higher than the natural resonance frequency of 1.2 GHz for Fe3O4 bulk. The minimum reflection loss (RLmin) of Fe3O4@SiO2 porous nanorods reached -59.49 dB at 8.89 GHz, and its effective bandwidth (RL < -10 dB) covered 4.52 GHz at a thickness of 3.18 mm. In addition, the radar scattering cross section (RCS) reduction value reached more than 48 dBm2 after removing the background. Our study provides insight into the relationship between anisotropy, core-shell structure, morphology of nanoparticles and corresponding microwave performance, and provides a reference scheme for the fabrication of high-performance lightweight microwave absorbing materials.

Scattering Properties of Non-Gaussian Ocean Surface with the SSA Model Applied to GNSS-R

Global Navigation Satellite System Reflectometry (GNSS-R) is an emerging earth observation method for remote sensing of feature parameters using reflected signals from navigation satellites, and is a purely specular bistatic forward scattering observation means with special right-handed circular polarization incident wave. In this paper, the small-slope approximation model of non-Gaussian sea surface is used as the basis to construct the scattering model for the observation geometry of GNSS-R as well as the L-band characteristics, and the fully-polarization normalized bistatic radar scattering cross section (NBRCS) are simulated by the method of polarization synthesis to analyze the scattering characteristics under different wind speeds and directions on the ocean surface, which highlights the variation of NBRCS with wind direction, and the scattering modeling accuracy is improved by comparing with the data of CYGNSS. In addition, we adopt the observation geometry deviating from purely specular geometry, discuss the scattering azimuth angle, scattering influence, and the relative relationship between different polarizations of the scattering angle under the non-specular geometry.

Research on multifunctional integrated multispectral stealthy metasurface absorbers for infrared and radar

Owing to the widespread application of multispectral combination detection technology in the military, the research of multispectral combination stealth technology has become imminent. To address that problem, an integrated ultra-broadband radar stealth and high-efficiency infrared stealth multispectral flexible stealth metasurface absorber (MFSA) is proposed, fabricated, and measured. The MFSA consists of an infrared shielding layer (IRSL) and a radar-absorbing layer (RAL). The simulation results of MFSA show that the absorptivity is higher than 90% in the radar stealth band 3.6 ∼ 29 GHz, the infrared emissivity is lower than 0.322 in the infrared stealth band 3–14 μm, and the MFSA achieves radar scattering cross-section (RCS) reduction in 3.6 ∼ 29 GHz effectively. In addition, the multiphysics simulation results at the peak frequency point show that the slight deformation of the structure caused by the heat loss effect of the MFSA on the electromagnetic (EM) wave has almost no effect on its absorptivity. After measuring, radar stealth properties and infrared stealth properties are verified. Due to flexibility, thin thickness (only 5.1 mm), excellent stability, wide incidence angle (0°∼60°), polarization-insensitive, ultra-broadband radar stealth, and high-efficiency infrared stealth indicate the designed MFSA has promising applications on military platforms and sites with multispectral combination stealth technology.

Composite wave-absorbing structure combining thin plasma and metasurface

In order to solve the thickness dependence of plasma absorption of electromagnetic waves and further reduce the backward radar scattering cross section (RCS) of the target, we designed a novel composite structure of a metasurface and plasma. A metasurface with three absorption peaks is designed by means of an equivalent circuit based on an electromagnetic resonance type metamaterial absorber. The reflection and absorption of the composite structure are numerically and experimentally verified. The finite integration method was used to simulate a composite structure of finite size to obtain the RCS. The experimental measurements of electromagnetic wave reflection were conducted by a vector network analyzer (Keysight N5234A) and horn antennas, etc. The research showed that the absorption capacity of this composite structure was substantially improved compared to either the plasma or the metasurface, and it is more convenient for application due to its low plasma thickness requirement and easy fabrication.

Highly dispersed Co/Co9S8 nanoparticles encapsulated in S, N co-doped longan shell-derived hierarchical porous carbon for corrosion-resistant, waterproof high-performance microwave absorption

It is highly desirable, but challenging to develop multifunctional electromagnetic wave (EMW) absorbing material for practical applications in some harsh environments. Herein, we successfully embedded highly dispersed Co/Co9S8 nanoparticles into a three-dimensional (3D) honeycomb porous carbon skeleton (the carbon skeleton is derived from longan shell-derived S, N co-doped porous carbon) as a multifunctional material with outstanding EMW absorption properties, hydrophobicity and corrosion resistance. Its superior versatility is attributed to synergistic effects of the S and N dopants, large specific surface area, abundant carbon defects, and 3D porous characteristics. Minimal reflection loss (RLmin) and efficient absorption bandwidth (EAB) of the optimized material as EMW absorbers can achieve −59.9 dB and 6.8 GHz at a thickness of 2.7 mm, respectively, which are superior to most of the reported carbon-based absorbents. Meanwhile, theoretical simulations of the radar scattering cross section (RCS) further confirm that this multifunctional material has outstanding EMW attenuation performance and actual application potential. In addition, the material possesses strong hydrophobicity (124°) and anti-corrosion properties, expanding the scope of potential applications of microwave absorbers. Therefore, this work provides an effective development strategy for the design of anti-corrosion, super-hydrophobic, and high-performance EMW absorbing materials.

Enhanced microwave absorption performance of large-sized monolayer two-dimensional Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; based on loaded Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; nanoparticles

With the rapid development of electronic equipment, electromagnetic interference and electromagnetic radiation pollution have become serious problems, because excessive electromagnetic interference will not only affect normal operation of electronic equipment but also do great harm to human health. In general, an ideal material for microwave absorption with the characteristics of high reflection loss (RL) intensity, wide effective absorption band (EAB), thin thickness, and lightweight could effectively consume electromagnetic wave (EMW) energy. Therefore, it is crucial to search for such an ideal microwave absorption material to deal with the electromagnetic radiation pollution. Two-dimensional (2D) carbon/nitride MXene has received more and more attention in recent years, because excellent electrical conductivity and rich surface-functional groups in MXene show positive effects on electromagnetic wave absorption. However, as a non-magnetic material with only dielectric loss, MXene exhibits obvious impedance mismatch, which greatly limits its practical applications. Combining MXene with magnetic materials becomes a hotspot for the exploration of ideal microwave absorption materials. As a typical ferrite, Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; shows excellent soft magnetic properties such as high saturation magnetization, high chemical stability, and simple preparation. In this paper, the 2D Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;@Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; composite is successfully prepared by hydrothermal method and simple electrostatic adsorption process. The Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; nanoparticles are uniformly anchored on the surface of large-sized monolayer Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;, which effectively reduces the stacking of MXene. By regulating the proportion of magnetic materials, the microwave absorption performance of 2D Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;@Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; composite is investigated. With the content of Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; nanoparticles in the 2D Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;@Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; composite increasing from 4 mg to 8 mg, the microwave absorption performance is enhanced obviously. This is caused by the abundant Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;/Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; interface, scattering channels, point defect, charge density difference in 2D Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;@Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; composite, and the optimized impedance matching. The minimum reflection loss (RL&lt;sub&gt;min&lt;/sub&gt;) of 2D Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;@Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; composite reaches –69.31 dB at a frequency of 16.19 GHz, and the effective absorption band (EAB) achieves 3.39 GHz. With the content of Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; nanoparticles further increasing to 10 mg, the microwave absorption performance shows a decreasing trend. Excessive Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; nanoparticles in the 2D Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;@Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; composite lead to the decrease of electrical conductivity and thus the impedance dis-matching and dielectric loss decreasing, which leads the microwave absorption performance to decrease. Radar scattering cross section (RCS) is a physical quantity that evaluates the intensity of the scattered echo energy in the intercepted electromagnetic wave energy. The results of the RCS simulation can be applied to real objects which have been widely utilized in radar wave stealth. Its multi-angle simulation results can be used as an important basis for evaluating the stealth capability of microwave-absorbing material. The RCS simulations show that the average RCS value of 2D Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;@Ti&lt;sub&gt;3&lt;/sub&gt;C&lt;sub&gt;2&lt;/sub&gt;T&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; composite is over –47.92 dBm&lt;sup&gt;2&lt;/sup&gt; at an incidence angle of 25°, demonstrating its excellent radar wave absorption performance. This study provides new ideas for improving and practically using two-dimensional and magnetic materials in the microwave absorption field and gives a new path to the subsequent development of microwave-absorbing composites.

An FFT-Based Implementation of the First-Order Small-Slope Approximation for Simulating Microwave Scattering From Sea Surface

This article presents a simple and efficient implementation of the first-order small-slope approximation (SSA-1) to simulate the normalized radar scattering cross section (NRCS) from ocean surface based on fast Fourier transform (FFT) of the equivalent sea surface autocorrelation function. The implementation process only takes a pair of FFT operations between sea wave spectrum and sea surface autocorrelation function. Compared with the reported implementations of SSA-1 model based on the series expansion, the proposed method (called as “FFT-based implementation”) reduces the computation amount of FFT operations greatly. To examine the accuracy and efficiency of the FFT-based implementation relative to the direct integration implementation of SSA-1 (called as “classical implementation”), the monostatic and bistatic NRCSs simulated by using the two implementations with the help of Elfouhaily sea spectrum at various radar frequencies and sea states are compared. The comparison results indicate the FFT-based implementation not only holds almost the same accuracy as the classical implementation but also has a higher efficiency, especially for the simulation scenarios with small Rayleigh parameters. Furthermore, we discuss the influence of sampling range and sampling interval of sea spectrum components on the accuracy and efficiency of the FFT-based implementation and its feasibility on the simplified second-order SSA (SSA-2) model with the mathematic expression similar to SSA-1. The simulation results show that the sampling range and sampling interval of sea spectrum have different effect on the accuracy and efficiency of the FFT-based implementation, and the proposed implementation method is also feasible for the simplified SSA-2 model.

Construction of Bi2S3/rGO heterointerfaces for enhanced and tunetable electromagnetic wave absorption

Low conductivity and poor impedance matching are typical challenges for metal chalcogenides to become highly efficient microwave absorbers(MAs). Here, we report efficient MAs composed of Bi2S3 nanorods and rGO. The conductivity of the composite was effectively improved by rGO. In addition, the heterointerfaces and conductive network formed by Bi2S3 nanorods and rGO significantly enhance conductivity and interfacial polarization loss. These loss mechanisms synergistically enhance microwave absorption. The optimal reflection loss among these composites is −21.34 dB with 2.2 mm thickness, and the widest effective absorption bandwidth(EAB) is 6.72 GHz, covering the entire Ku band, X band can be covered after thickness adjustment. The finite element simulation results and radar scattering cross section(RCS) simulation results indicate that Bi2S3/rGO-40 composite has good microwave absorption capability in practical applications. This work provides an essential reference for improving metal chalcogenides MAs to achieve effective electromagnetic wave absorption loss in multiple frequency bands.

Design and study of a new broadband RCS carbon-glass fiber hybrid metamaterial

In this paper, a plain-woven metamaterial consisting of a ribbon-like blend of carbon fiber-glass fiber strips is proposed. The structure of the proposed hybrid material has a broadband filtering function of electromagnetic wave, can form beam reconstruction and selective wave transmission, and reduce radar scattering cross section (RCS) in the 9 GHz - 25 GHz frequency band. The macroscopic equivalent mechanical parameters are estimated by constructing the micro fine structure model and combining the periodic boundary conditions. The Hasin failure criterion is used to predict the progressive damage evolution of the proposed hybrid material under tensile loading. In addition, the plain-woven metamaterial has the advantages of simple structure and easy fabrication, which provides a new design idea for the metamaterial radome and important engineering guidance for its fabrication process.

Analysis of electromagnetic scattering from typical targets for orbital‐angular‐momentum waves: Theoretical model

The target scattering characteristics in microwave band are necessary to be researched for Orbital-Angular-Momentum (OAM) wave-based radar applications. A theoretical description of electromagnetic (EM) scattering from a typical target by OAM waves is proposed in this paper. First, OAM waves are decomposed into plane waves in the spectral domain with different elevation and azimuth angles. Then, the scattering form of each decomposed plane wave is determined through coordinate system transformation and physical optics approximation. Formulas and numerical results are presented for OAM-based radar scattering cross section of a perfect electric conductor and dielectric plate and a cylinder. Unlike the conventional results of EM plane wave scattering, the scattering properties of OAM waves from plate and cylinder are analysed with particular emphasis on OAM mode influence. The results provide insights into OAM wave-matter interactions and may find important applications in wave propagation and OAM wave-based radar detection and imaging.

Characteristics and experimental study of radar scattering foil

Aiming at the current situation that Doppler radar can use the echo frequency difference to avoid the interference of chaff and chaff clouds, by studying the average radar scattering cross section, bandwidth characteristics, horizontal drift speed, polarization characteristics of the foil. The performance of the Paller effect, etc., examined the foil’s ability to counter Doppler radar. The static test is used to test the performance of the foil. Experimental research shows that the composite foils of multiple sizes can increase the reflection loss of the composite foil and improve the interference efficiency. Uses round foil as the base material, and foil with mixed side length of 10mm can enhance the loss performance under various polarization conditions.

Developing and Testing Models for Sea Surface Wind Speed Estimation with GNSS-R Delay Doppler Maps and Delay Waveforms

This paper focuses on sea surface wind speed estimation based on cyclone global navigation satellite system reflectometry (GNSS-R) data. In order to extract useful information from delay-Doppler map (DDM) data, three delay waveforms are presented for wind speed estimation. The delay waveform without Doppler shift is defined as central delay waveform (CDW), and the integral of the delay waveforms with different Doppler shift values is defined as integral delay waveform (IDW), while the difference between normalized IDW (NIDW) and normalized CDW (NCDW) is defined as differential delay waveform (DDW). We first propose a data filtering method based on threshold setting for data quality control. This method can select good-quality DDM data by adjusting the root mean square (RMS) threshold of cleaned DDW. Then, the normalized bistatic radar scattering cross section (NBRCS) and the leading edge slope (LES) of IDW are calculated using clean DDM data. Wind speed estimation models based on NBRCS and LES observations are then developed, respectively, and on this basis, a combination wind speed estimation model based on determination coefficient is further proposed. The CYGNSS data and ECMWF reanalysis data collected from 12 May 2020 to 12 August 2020 are used, excluding data collected on land, to evaluate the proposed models. The evaluation results show that the wind speed estimation accuracy of the piecewise function model based on NBRCS is 2.3 m/s in terms of root mean square error (RMSE), while that of the double-parameter and triple-parameter models is 2.6 and 2.7 m/s, respectively. The wind speed estimation accuracy of the double-parameter and triple-parameter models based on LES is 3.3 and 2.5 m/s. The results also demonstrate that the RMSE of the combination method is 2.1 m/s, and the coefficient of determination is 0.906, achieving a considerable performance gain compared with the individual NBRCS- and LES-based methods.

Strong, omnidirectional radar backscatter from subwavelength, 3D printed metacubes

Metallic metacubes formed of six metal plate faces connected via a metal jack are shown to backscatter microwave radiation extremely powerfully. Experimental radar scattering cross-section (RCS) data from 3D printed samples agrees very well with numerical model predictions, showing an RCS of fifteen times the geometrical cross section. The principal resonance of the metacubes demonstrates near-complete independence of the incident angle or polarisation of the radiation, making the metacube an omnidirectional scatterer. The metacubes are fabricated via additive manufacturing from metal-coated polymer, and are extremely lightweight, making them excellent candidates for improving the radar return signals from small objects such as drones and cubesats.

Study of the Terahertz Wave Scattering From Metal Surface Coated by Rough Lossy Coating Based on a Ray Tracing Modeling

A ray tracing method based on the geometrical optics and physical optics approximation is proposed for calculation of the scattering from rough metal surface with rough coating in terahertz regime. Geometrical optics is utilized to describe the wave propagation concerning the reflection and transmission, whereas physical optics is applied to obtain the scattering fields by equivalent currents on the surfaces. The method provides a reliable treatment of scattering from rough layers involving identical/different roughness. The scattering predictions of the rough layers are compared to the multilevel fast multipole algorithm (MLFMA) to demonstrate the efficiency and accuracy of the proposed method. Once validated, we use the method to carry out a sensitivity study of the bistatic radar scattering cross section to variations in layer parameters of interest in terahertz coating target detection, such as the roughness of the coating and metal surface, thickness of the coating layer.

A Modified EM Algorithm for ISAR Scatterer Trajectory Matrix Completion

The anisotropy of radar cross section of scatterers makes the scatterer trajectory matrix incomplete in sequential inverse synthetic aperture radar images. As a result, factorization methods cannot be directly applied to reconstruct the 3-D geometry of scatterers without additional consideration. We propose a modified expectation-maximization (EM) algorithm to retrieve the complete scatterer trajectory matrix. First, we derive the motion dynamics of the projected scatterer, which approximates an ellipse. Then, based on the estimated ellipse parameters using the known data of each scatterer trajectory, we use the Kalman filter to initialize the missing data. To address the limitations of a traditional EM, which only considers the rank-deficient characteristics of the scatterer trajectory matrix, we propose to augment EM by using both the known rank-deficient and elliptical motion characteristics. Experimental results on simulated data verify the effectiveness of the proposed method.

A Structured Grid Finite-Element Method Using Computed Basis Functions

Structured (e.g., rectangular) meshes in finite-element (FE) analysis offer several advantages, but are not often used because of the error introduced in fitting material interfaces. The nonconforming voxel FE method (NVFEM) is a hierarchical structured method that systematically reduces the geometric error in an adaptive way, but it requires large numbers of elements and therefore is expensive. By computing basis functions that take into account the interface cutting through an element, the number of elements needed is greatly reduced. The resulting method, CBF-NVFEM, is applied to the computation of the radar cross section of free-space scatterers. Results indicate that CBF-NVFEM is much more efficient than NVFEM and is competitive with FEM using unstructured meshes of tetrahedra.

Bayesian classification of the ice cover of the Arctic seas

A classification of sea ice in the Arctic by age (multiyear; first-year; and first-year deformed ice, nilas, etc.) is developed based on the Bayesian approach using satellite radar data and taking into account regional peculiarities of these types of ice for different sectors of the Arctic. Estimations of a priori probabilities for each ice type, which are required for the use of the Bayesian classification, are obtained by the analysis of ice charts in the Arctic seas developed at the AARI in 2008–2013 using satellite data. A posterior probabilities are estimated visually by an expert. Types of sea ice distinguished by the expert on satellite images make it possible to create sample values of the radar-scattering cross section (RSCS). Examples of the proposed Bayesian classification of ice in the Laptev Sea according to Envisat satellite data are given.